title: Detection of chromosomal blaCTX-M-15 in Escherichia coli O25b-B2-ST131 isolates from the Kinki region of Japan.
abstract: Escherichia coli O25b-B2-ST131 isolates harbouring bla(CTX-M-15) are distributed worldwide. The bla(CTX-M-15) transposition unit has often been found on plasmids and the genetic contexts have been examined; however, less is known about the frequency and contexts of the bla(CTX-M-15) transposition unit on the chromosome. This study was performed to determine the chromosomal location of the bla(CTX-M-15) transposition unit and to analyse the molecular structure of the region surrounding the bla(CTX-M-15) transposition unit in E. coli O25b-B2-ST131 isolates. Twenty-two E. coli O25b-B2-ST131 strains harbouring bla(CTX-M-15) that had been isolated from university hospital patients and nursing home residents in the Kinki region of Japan were examined. Inverse PCR (iPCR) targeting bla(CTX-M-15) was performed to classify the molecular structure of the region surrounding the bla(CTX-M-15) transposition unit. The isolates were classified into nine types (types A-I) considering the iPCR results; type A was the most prevalent type (13/22 isolates). Sequences of the iPCR-amplified DNA fragments showed that the bla(CTX-M-15) transposition unit consisted of ISEcp1, bla(CTX-M-15) and orf477Δ. A homology search of the obtained sequences showed that the bla(CTX-M-15) transposition unit was inserted into different chromosomal regions in eight of the nine classified types. Although 21 of the 22 E. coli isolates possessed chromosomally located bla(CTX-M-15) transposition units, clonal spread was not evident on pulsed-field gel electrophoresis (PFGE) analysis. Taken together, these data indicate that certain E. coli O25b-B2-ST131 strains harbouring chromosomal bla(CTX-M-15) have emerged and spread in the Kinki region of Japan.
authors.affiliation: Department of Biomedical Informatics, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan; Japan Science and Technology Agency/Japan International Cooperation Agency, Science and Technology Research Partnership for Sustainable Development (JST/JICA, SATREPS), Japan; Laboratory of Microbiology, School of Health Sciences, Faculty of Medicine, University of the Ryukyus, Okinawa 903-0215, Japan. Electronic address: hiraii@med.u-ryukyu.ac.jp.
authors.forename: Itaru
authors.initials: I
authors.lastname: Hirai
authors.forename: Naoki
authors.initials: N
authors.lastname: Fukui
authors.forename: Masumi
authors.initials: M
authors.lastname: Taguchi
authors.forename: Kou
authors.initials: K
authors.lastname: Yamauchi
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Nakamura
authors.forename: Sho
authors.initials: S
authors.lastname: Okano
authors.forename: Yoshimasa
authors.initials: Y
authors.lastname: Yamamoto
mesh_terms: D000368:Aged; D002876:Chromosomes, Bacterial; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics*; D016521:Electrophoresis, Gel, Pulsed-Field; D004926:Escherichia coli / Q000145:classification / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology*; D056426:Genetic Loci; D006801:Humans; D007564:Japan; D008969:Molecular Sequence Data; D058889:Molecular Typing; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D001618:beta-Lactamases / Q000235:genetics* / Q000378:metabolism
chemical_list: D004251:DNA Transposable Elements; D004269:DNA, Bacterial; C473109:beta-lactamase CTX-M-15; D001618:beta-Lactamases
keywords: CTX-M-type extended-spectrum β-lactamase; Chromosomal location; ESBL; Escherichia coli O25b-B2-ST131; bla(CTX-M-15)